Fix freeform window can't resize after maximize window and restore

The freeform window mode would change to fullscreen if it maximzed
window size, that could set the touch region crop to its stack bounds.
And we should clear that after it restore to freeform window mode.

Bug: 152248369
Test: enter freeform window mode, open an app and maximize it,
      restore and resize it.
Change-Id: I7249a682ca3ed0f4ce89fc05413c8d24c8dc83de